It is August of 1704, and Matthew Corbett and his companions have narrowly escaped the island of Golgotha and are recuperating in the town of Alghero on the northwestern coast of Sardinia, currently under Spanish rule. Hudson Greathouse is at his limits, both mentally and physically, after their harrowing ordeal.
Their respite is short-lived when the Spanish authorities learn of their abandoned quest for Brazio Valeriani and the mirror created by his father, Ciro. This mirror is rumored to have the power to summon demons from the underworld, and the Spanish authorities are eager to possess it. Consequently, a professional witch-hunter and soldiers are assigned to accompany Matthew, Hudson, Professor Fell, and Cardinal Black as they resume their quest.